Sitting in front of us are three "computers:" a tablet, a new ultrabook and a so-called convertible device that can be used as an ultrabook or tablet. An ultrabook, loosely defined, is a thinner, lighter laptop without an internal CD/DVD drive and a smaller solid state hard drive.

There are many similarities between the three devices:

They all need either Android or Windows operating systems to run

They all have ultrafast processors and great graphics

They all run the apps and programs we have become dependent upon

They all cater to work and home environments

They're all slimmer and lighter than previous models

But, there are also enough differences to make them all valuable tools for the casual user and the professional.

The Samsung Galaxy Tab S ($499 for 16 GB, 10.5 inches), for now, is the biggest and brightest of the Android tablets available (there's also an 8.4-inch version for $399).

We've been playing with the Tab S for a couple of weeks and it has become our go-to device for Android applications. It packs enough processing power to run graphics smoothly and has the ability to run two applications side-by-side without sacrificing video or speed.

As with previous Samsung Galaxy devices, the Tab S includes a fingerprint scanner that can be a bit uncooperative at times. To solve this problem, you can bypass the scanner and enter a password to get access to your programs.

We were delighted with the graphics power of this tablet. We were able to watch UtraViolet movies we have stored on Flixster without the annoying rebuffering delays we've found on most tablets.

Among its key features are:

Super AMOLED display which is twice the resolution of HD

An eight megapixel rear camera and a two megapixel rear camera

It's about a quarter-inch thick and weighs one pound.

You can add up to 128 gigabytes of storage using the built-in micro SD card slot

It boasts up to nine hours of battery life

The tablet we tested also came with a Simple Cover ($39.95) that attached to the back of the unit via two push buttons. Although it serves only as a protective cover for the device, there are other cases and accessories that are specifically made to "hook up" with the tab, including a Book Cover, which offers a bit more protection and can be used as a stand.

Hewlett Packard's EliteBook Folio 1040 G1 ($1,299 for the model we tested) has enough new features to make it worth the purchase price.

The first thing you notice is how thin it is. The folks at HP say it's the thinnest ultrabook on the market at a hair more than a half-inch thick. It also weighs in at 3.3 pounds.

After flipping up the screen you immediately notice the absence of buttons at the bottom of the computer's touchpad. Users, instead, either tap on the bottom right or left sides of the pad to access the functions they used to have with the buttons. You can also tap one finger anywhere on the pad for left click functions and two times for right button functions. This takes some time to get used to, but this is becoming the standard on many new laptops and ultrabooks, so we'll have to get used to it.

The unit we played with had an Intel i5 processor and came preloaded with Microsoft Windows 8.1 Pro 64. It also had a 14-inch touchscreen, a 256 gigabyte solid state hard drive and four gigabytes of RAM. You can also spend a few hundred dollars more to get it with an i7 processor and eight gigabytes of RAM, but, truthfully, unless you're a power user, you don't need it.

We were a bit annoyed that it only had two USB 3.0 ports (one is a charging port) and gave us only four hours before we had to recharge the battery. But, on the whole, its features greatly outweighed its drawbacks.

It has a multi SD card reader that can handle SD, Micro SD, SDHC and HDXC memory cards

The 14-inch display is one of the brightest among laptops we've tested

Its built-in audio and speakers aren't much to brag about, but it does have a port for headphones

It has a dual-array microphone, although the webcam is optional

It supports all of the wireless standards and Bluetooth

It comes with a side dock adapter for VGA and Ethernet connections

The Dell Inspiron 11 300 Series 2-in-1 ($399.99 to $529.99 depending on configuration) can be used as an ultrabook or a tablet.

The one we played with came with a 500 gigabyte SATA hard drive, four gigabytes of RAM and an Intel Pentium N3530 processor, which is a hair faster than an Intel i3 and almost as fast as an Intel i5.

It's a bit smaller and thicker than the HP we tested, with an 11.6-inch touch screen and only weighs 3.1 pounds. But the thing that sets it apart from the others is the screen's ability to fold 360 degrees so it lays flat allowing it to be used as a Windows tablet. The one drawback here is that it folds back onto the bottom of the case instead of covering the keyboard. This means that your hands could accidently hit keys or the touchpad when holding it.

Like the HP, there aren't any buttons on the touchpad, so you need to use the process we described above to access right-click and left-click functions.

Key features include:

Three USB ports (one 3.0 and two 2.0) and an HDMI port

An MMC and SD-card reader

A built-in webcam and microphone

Built-in WiFi and Bluetooth

Microsoft Windows 8.1 Pro 64

The battery is rated at about nine hours, but we were only able to get an average of seven hours from a full charge. And, as with the HP, we had to get used to the buttonless touchpad, but, in the name of innovation, we're getting better at it.